Installing an outboard motor on a boat is a critical step in preparing the boat for the season, on which your safety, the handling of the vessel and the resource of the engine itself depend. Incorrect installation can lead to cavitation, overheating of the engine, reducing speed or even losing the screw and engine while driving. In this article, we will discuss in detail all the nuances of how to attach the motor to the tray to eliminate risks and get the most out of your water kit.
The installation process requires attention to detail, as the squirrel board experiences tremendous loads from traction and vibration. We will consider the choice of the height of the diewood installation, the correct use of rods, work with squirrel plates and typical beginner errors that often lead to breakdowns of expensive equipment.
Preparation of the transaxboard and selection of the installation site
Before starting installation, you need to carefully inspect squirt-boardIt should be perfectly flat, without cracks, rot (for wooden transoms) or corrosion (for metal ones). The surface to which the motor will fit must be smooth to ensure tight contact of the rods and exclude the backlash. If you install the motor for the first time, make sure that the transom will withstand the weight and power of the chosen model.
Tightening the engine relative to the diametric plane of the boat is the first step that cannot be ignored. Shifting the motor to the left or right will cause the boat to be constantly steered away, which will require constant thrustering and create an uneven load on the hull. Use roulette to find the center of the transom, and make time marks.
Use a soft marker or paint tape for time stamps on the transom so as not to damage the lacquer or painted coating of the boat.
If your boat is installed sink-board It's a simplified process, because it already has guides or markings, and if you put the motor directly on wood or fiberglass, it's important to make sure that there are no internal bulkheads at the mounting site that can interfere with the bolts, or vice versa, that the structure is reinforced.
Selecting the height of the installation of lower unit above water
One of the most difficult questions for beginners is to determine the correct height of the motor attachment. Anti-cavitation plate For most planing boats, the optimal position is when the lower plane of the plate is in the same plane with the bottom line or lower by 10–25 mm.
Too low an engine installation increases water resistance, leading to fuel overruns and lower top speeds. In addition, the engine can run unsteadily at idle speeds. Too high an engine can trap air with a propeller (cavitation), especially on turns or at sharp acceleration, causing overheating and loss of traction.
For flat bottom boats, the motor is often lower than for boats with a deep V-shaped keel, which is related to the angle of water lift when moving. PVC inflatable boats You should be especially careful: due to the softness of the cylinders, the transom can “play”, so it is better to choose the height with a small margin down.
What is cavitation and how is it dangerous?
Cavitation is the formation of vapor bubbles in the low-pressure zones behind the propeller blades, and when these bubbles collapse, a shock wave occurs, which destroys the metal of the screw and the anti-cavitation plate, and also dramatically reduces the efficiency of the engine.
The height test is done only on the water. Once the engine is set to its intended height, you need to go out for planing. If you see a lot of milk water behind the screw and you see a drop in speed, the engine is too high. If the boat is nasal and does not get on plane at normal speeds, maybe the engine is buried excessively.
Fixing mechanism: rods and bolts
There are two main ways of fixing the outboard motor: on removable rods (clamp screws) and on the bolt connection. rod-cutter It allows you to quickly remove and install the motor, which is convenient for storage and transportation, but this method requires regular checks of tightening of the screws, as vibration can weaken them over time.
A bolt connection is considered more reliable and safe for powerful engines (usually 15-20 hp and above), in which case the motor actually becomes part of the boat structure, to do this, holes are drilled in the transom and flange of the lower unit, and the motor is attached through bolts using growers and counternuts.
When using rods, it is important not to over-tighten them so as not to deform the tanning board or the body of the lower unit, but also to leave no gaps. Metal pads between the rod and the translucent can help distribute pressure and protect the tree from being pressed. Always use a thread fixator (for example, Loctite 243) on threaded joints subject to vibration.
If you use a bolt connection, be sure to use it. sealant for holes in the transom to prevent water from entering the hull of the boat and material layering. Bolts must be of stainless steel of the appropriate strength class to avoid corrosion and break under load.
Adjustment of the angle of inclination (different) and course stability
Adjustment differentiation (trim) allows you to change the angle of inclination of the engine relative to the transom, which directly affects the position of the bow of the boat when moving. On the lower unit of most engines there are a number of holes for mounting a thrust finger or hydraulic / electric trim. Proper adjustment of the angle of inclination optimizes the boat's course and saves fuel.
If the boat's nose is too raised when going out for planing, the boat can start to "goat" (jumping along the waves), which is dangerous and uncomfortable. In this case, the engine must be tilted forward (lowering lower unit). If the nose is heavily buried in the water and the boat does not go into plane, creating a high wave, lower unit must be deflected back (lift).
| A symptom. | Reason. | Action. |
|---|---|---|
| Boat goes goat, nose goes up | Too much engine back deviation | Lower the lower unit (tilt forward) |
| Boat doesn't plane, high consumption | Nose too deep in the water | Raise lower unit (tilt back) |
| Difficult to keep course ( yaw) | The wrong angle of Trim or wear of persistent washers | Check wear and adjust the angle |
| The screw grabs air on the turns | The engine is set too high or jacked up | Lower the engine or change the angle of inclination |
Setting the angle of inclination also depends on the boat loading. When passengers and gear are fully loaded, the boat's nose lowers, and additional trimming may be needed to compensate for the weight. Experiment with the position of a stubborn finger in calm water to find the "middle ground" for your particular kit.
The ideal angle of the trim allows the boat to plane at minimum engine speeds with a flat bottom, without burrowing with the nose or excessive buoyancy.
Use of trans-shipment plates and parsers
Often, the standard transom height (usually 381 mm or 508 mm) is not enough to properly install the engine, especially on older boats or boats with non-standard architecture. cross-plate They allow you to raise the mounting point of the engine, ensuring that the propeller works properly.
Trans slabs are made of moisture-resistant plywood, aluminum or fiberglass, and it is critical to ensure that the joint between the plate and the main transom is sealed when installed, and that the water that gets between them will cause the wood to rot or corrosion of the metal, which will eventually lead to the collapse of the structure.
⚠️ Attention: When using a wire or a slab, the length of the motor mount bolts must be increased accordingly. The use of standard bolts can lead to the fact that the thread does not catch completely and the motor can come off at full speed!
There are also adjustable transom plates that allow you to change the angle of the motor in a wide range without using holes in the lower unit. This is convenient for choosing the optimal differentiation, but adds additional weight and complexity to the design. Make sure that your boat will withstand the additional weight of the metal plate and the engine itself.
Security and final check before launch
Once the motor is fixed, the height and angle are exposed, a thorough final check must be made. counternuts Check if the gas cable is twisted and if the cooling system hoses are clamped.
Be sure to use a safety cable (falin) for the motor, especially if it is attached only to rods. The cable is attached to one end on the rig on lower unit, and the other to a reliable part of the boat hull (for example, to a ditch on a transom or leer), which will save the engine from loss in the event of failure of the strub.
☑️ Final check before launching
The first launch is best done on water, but in a safe place, away from bathers and other boats. Listen to the engine: there should be no extraneous vibrations, knocks or whistles. If the boat is not behaving properly at speed, immediately turn off the gas and check the settings.
⚠️ Attention: Never leave the motor in a lowered position in shallow water or off the coast unattended. Excitement can sharply lift the boat and the screw will hit the bottom, causing the lower unit or gearbox to break.
Frequently Asked Questions (FAQ)
Can I attach the motor to the PVC boat transom without a transomboard?
It is absolutely impossible to attach the motor directly to the soft cylinder. To install the engine on an inflatable boat, a rigid transom board (usually plywood) is required, which distributes the load. Some boat models have a built-in inflatable transom with a rigid insert, but even in this case it is recommended to use an additional plywood lining to protect the material.
How often do I need to pull up the engine rods?
Checking the puffs of the rods is recommended before each step into the water. Vibration and shocks to the wave can weaken the mounting. If you notice that the motor has started to "walk" or shift while driving, immediately stop and tighten the screws. For bolt connection, the check is required less often - once a season or after 50 hours.
Do I need to lubricate the contact points of the trunk and the trunk?
Yes, it is useful to do this to prevent metal from sticking and corrosion protection. Use water-repellent lubricants (such as lithium or marine sprays), but make sure that the lubricant does not get on rubber seals, if any, as some oil products can break down rubber.
What to do if the screw is constantly getting air?
If the propeller is getting enough air, check the height of the engine, it may be too high, it may be the wrong angle of the differential (too up your nose), try lowering the motor lower or changing the position of the thrust finger, if the problem persists, it may be that the pitch of the propeller is too large for the boat and the power of the engine.